<!DOCTYPE html>
<html lang="ch">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title></title>
    <style>
    .div{
        width:0px;
        height:0px;
        border:10px solid transparent;
        /* border-top-color:lightseagreen; */
        /* border-left-color:lightseagreen; */
        /* border-right-color:lightseagreen; */
        border-bottom-color:lightseagreen;
    }
    </style>
</head>
<body>
   <div class="div"></div>
</body>
</html>